How and why volcanoes erupt
Volcanoes are geological formations that arise over cracks in the earth's crust. This is due to the fact that through them lava, gases and rock fragments can come out to the surface. Such a process is called “volcanic eruption”.
What is causing this process?
Causes of volcanic eruptions - layers of magma, which is located under them. Under normal conditions, it is under great pressure, and through cracks in the bark comes out. For comparison, you can give an example: if you shake a bottle with any carbonated drink, and then open it, the contents will flow very violently outside.
How does a volcanic eruption occur?
Volcanic earthquakes and loud noise may be precursors of activity. An eruption usually begins with the release of gases with particles of cold lava, which are gradually replaced by red-hot debris. Sometimes this stage may be accompanied by the outpouring of lava. The height of the emission ranges from one to five kilometers (the highest column of substance appeared during the eruption of the Bezymyanny volcano in Kamchatka - forty-five kilometers).After that, the emissions are transferred to distances of several tens of thousands of kilometers, and then deposited on the surface of the Earth. Sometimes the concentration of ash can be so high that even sunlight does not penetrate it. During the eruption, alternating strong and weak lava emissions occur. After a while, culminating paroxysm occurs - an explosion of maximum power, after which the activity declines. The consequences of volcanic eruptions are dozens of cubic kilometers of spilled lava, as well as tons of ash that falls both to the surface and to the atmosphere.
What groups are volcanoes divided into?
- By activity - extinct, asleep, acting.
- The shape of the cracks of the bark is central and fissure.
- In appearance of the volcano - cone-shaped, dome-shaped, flat thyroid.
What is the eruption of volcanoes?
This process can also be characterized from several sides. For example, in terms of time, eruptions are long (up to several centuries!) And short-term (several hours). Eruption products can be solid (rocks), liquid (lava) and gaseous.
Types of Eruptions
- Hawaiian.It is characterized by emissions of liquid basaltic lava, which forms flat shield volcanoes.
- Strombolian. Lava is more viscous, slag cones form during explosions.
- Plinian's. Powerful, sudden explosions and emissions of a large amount of tephra, which forms ash and pumice streams.
- Peleysky. The formation of huge hot avalanches or clouds. After an eruption, a column of viscous magma, a few hundred meters high, may appear on the surface of the volcano.
- Gas (phreatic). Volcanic eruptions of this type are characterized by the ejection of solid rocks without the participation of new, liquid magma. This is usually a weak process.
- The ice. Volcanoes located under glaciers can cause very dangerous cataclysms: lahars, floods, or spherical lava. Fortunately, such eruptions are very rare.